1. Technical Field
This invention relates to a coated article comprising a member such as a protective member having light transparency, weather resistance, heat resistance and electrical insulation or a protective member having improved substrate passivation properties, and especially, to a solar battery module using the same.
2. Background Art
From the past, a variety of polymeric materials have been investigated as a protective member on module sheets requiring light transparency and weather resistance and themselves having flexibility, and having to be wound up and extended as used in solar batteries or the like.
For example, JP-A 1-198081 discloses an integrated a-Si solar battery in the form of a module sheet comprising a polymeric film support, thin film solar cells formed thereon, and a protective film layer stacked thereon with an intervening buffer adhesive film layer of a thermoplastic polymer, wherein the sheet has a thickness of less than 1000 xcexcm and a flexural modulus, as measured on a sample of 5 mm wide, of up to 100 kg-mm2, preferably up to 10 kg-mm2. The solar battery is repeatedly foldable and flexible so that the solar battery can be wound up into a compact roll when unnecessary without damaging the solar battery, and extended flat for operation when necessary.
Also, Japanese Patent Application No. 10-54498 of the present applicant describes a solar battery which is laminated to at least one surface of a substrate made of a resin having light transparency and heat resistance, using a hot melt member having a buffer adhesive layer containing a thermosetting resin.
These protective members of polymers (i.e., resins), however, sometimes fail to provide sufficient strength because polymers necessarily contain, by reason of synthesis, oligomers having a lower degree of polymerization which are considered to become sites where degradation begins. Also polymers have a limit on their heat resistance even when they are heat resistant. For example, when heated by direct exposure to sunlight, polymer film undergoes thermal shrinkage or expansion, which can eventually cause device deformation or delamination. When polymers are used in film form, problems of warp, crease, waviness and sagging occur. Further, since solar batteries to be installed outdoor for a long term are exposed to rain and wind as well as heat, they must be improved in weathering properties including water absorption, moisture permeability, oxygen permeability, barrier properties against gases including corrosive gases such as NOx, and hydrolytic degradation of polymers by interaction with UV light. Also, since solar batteries function upon receipt of light, typically sunlight, it is prohibited to use a material that can adversely affect the light transparency of a light receiving surface. Where flexibility must be maintained, it also becomes a restrictive factor.
When highly heat resistant films such as polyimide and aramides films are used as the substrate, these films which are strongly hydrophilic absorb water or moisture and give rise to outgassing in a vacuum deposition step of a solar battery module fabrication process. As a result of outgassing, electrodes and thin films such as photoelectric conversion films are deteriorated in quality; thin film laminates including substrates are curled, warped or waved; and factors associated with dimensions and shape deformation including a heat shrinkage factor and a coefficient of linear expansion are adversely affected.
Such protective members requiring light transparency, weather resistance, heat resistance, gas barrier properties, water (or moisture) non-absorbing properties, chemical separation resistance and the like are not only employed in solar batteries, but are also required in electronic device applications such as optical discs, liquid crystal panel displays, and EL displays and agricultural material applications such as vinyl chloride substitutes in agricultural green houses.
An object of the invention is to provide a coated article which is improved in light transparency, heat resistance, passivating properties (such as gas barrier properties, oligomer release prevention and outgassing minimization), water (or moisture) non-absorbing properties, stability against chemical degradation, dimensional shape stability, surface anti-reflection, electrical insulation, UV degradation resistance and weather resistance, and has such a member as a protective member featuring high productivity as typified by possible deposition under atmospheric pressure; and a coated article having such a member as a protective member imposing a minimized burden to the environment. Another object is to provide a solar battery module comprising a member such as a protective member as mentioned above, and experiencing little or no loss of performance for a long term of outdoor installation.
A further object is to provide a transparent flexible support suited for use in organic EL displays, and an organic EL display using the support.
These and other objects of the invention are achieved by the present invention which is defined below.
(1) A coated article comprising a substrate made of a resin having light transparency and heat resistance, stainless steel base metal material or glass, and a silica coating formed on at least one surface of the substrate by applying a polysilazane-containing coating solution under atmospheric pressure, followed by oxidizing treatment.
(2) The coated article of (1) wherein the polysilazane is perhydropolysilazane.
(3) The coated article of (1) wherein said silica coating has a thickness of 0.01 to 15 xcexcm.
(4) The coated article of (1) wherein said substrate is made of a resin having a glass transition temperature of at least 65xc2x0 C. or a heat resisting temperature of at least 70xc2x0 C.
(5) The coated article of (1) wherein said silica coating further has UV absorbing properties.
(6) The coated article of (1) wherein said silica coating further contains UV-absorbing inorganic microparticulates and/or an UV long wavelength-fluorescence converting organic compound or organic metal complex molecule.
(7) The coated article of (1) wherein said silica coating is stacked with an organic UV absorber-containing resin coating layer or a UV-absorbing polymer coating layer.
(8) The coated article of (1) wherein said substrate is made of at least a polymethyl methacrylate resin, polycarbonate resin, amorphous polyolefin resin or polyester resin.
(9) The coated article of (6) wherein said UV-absorbing inorganic microparticulates are ZnO microparticulates.
(10) The coated article of (1) wherein said silica coating is formed on one or either surface of said substrate for blocking the discharge of an outgassing component or oligomer in the substrate made of a water absorbing, moisture permeable or oxygen permeable resin film, so that the coated article functions as a passivation film and is used as a substrate for vacuum deposition.
(11) The coated article of (1) wherein said silica coating is formed on one or either surface of said substrate, wherein by virtue of the heat resistance, modulus of elasticity and low heat shrinkage factor of said silica coating, when another functional film is deposited and laid thereon under atmospheric pressure or vacuum, the coated article serves as a film depositing substrate capable of maintaining the dimensional precision, suppressing the heat deformation and maintaining the flatness of the substrate.
(12) A solar battery module comprising the coated article of (1).
(13) The solar battery module of (12) wherein said substrate has the silica coating on one surface thereof and a buffer adhesive layer on another surface thereof, and said module has the silica coat-bearing substrate attached as a protective member through the buffer adhesive layer.
(14) The solar battery module of (13) which has the protective member on at least a light-receiving side.
(15) The solar battery module of (14) which has the protective member on both the light-receiving side and an opposite side.
(16) The solar battery module of (12) which has a member comprising a substrate made of a stainless steel base metal material and a silica coating formed on one or either surface thereof as an insulating flat film.
(17) The solar battery module of (12) which has a member comprising a substrate made of soda glass and a silica coating formed on one or either surface thereof as a Na+ non-migrating film.